If I just use a DAC, do I need a Pre-amp?

I faced the same question, having found that adding a preamp always brought sound quality down a notch, compared to a simple analog volume control. My solution was the Schiit Saga preamp, which is passive if you want it to be, and has the option of adding a tube buffer should the impedances of your system be incompatible with a pure passive. The volume control is completely analog.  As an added plus, it has a remote control, and it was less than $400. The new versions, the Saga + and the Saga S, are tube buffered, or solid state buffered, respectively. As with the original, the buffer is optional and can be turned on or off with the remote.